[llvm] [Dexter] Use continue when resuming lldb execution to reach breakpoint (PR #156481)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer updated https://github.com/llvm/llvm-project/pull/156481

>From fac05cf25ab0a8e0cd91a3dc975ad56fde0dcfd7 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <stephen.tozer at sony.com>
Date: Tue, 2 Sep 2025 16:51:18 +0100
Subject: [PATCH 1/2] [Dexter] Use continue when resuming lldb execution to
 reach breakpoint

Currently, Dexter's interface for lldb and lldb-dap has a post-step hook
that checks to see whether lldb reports that we stopped because we
completed a step, and if so checks to see whether the current $pc address
also matches a known breakpoint whose conditions (if any) are met, and if
so it requests to "step in", so that we "resume" execution, stopping again
at the current address, such that lldb now reports that we have hit a
breakpoint and provides the list of breakpoints that were hit.

This logic has a flaw however: the call to "step in" sets an implicit
breakpoint on the next line. In Dexter's default stepping mode this is not
an issue, as we intend to step there eventually. When we use DexContinue,
however, we set a breakpoint from which we wish to continue to the next
user-specified breakpoint, rather than stepping. Currently, there is a bug
where Dexter sets a DexContinue breakpoint, arrives at that bp from a step,
requests "step in" so that LLDB gives us the hit breakpoint ID, requests
"continue" to hit the next user breakpoint, and then arrives at the next
line after the continue due to the earlier "step in" request. This
effectively negates the DexContinue command.

This patch fixes this behaviour by using "continue" instead of "step in" in
the post-step hook, ensuring that no implicit breakpoint is set so that we
do not incorrectly stop at the next line.
---
 .../debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py          | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py b/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
index dec12b9bc83da..e3d0c4ec192d3 100644
--- a/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
+++ b/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
@@ -232,7 +232,7 @@ def step_in(self):
                     ):
                         stepped_to_breakpoint = True
             if stepped_to_breakpoint:
-                self._thread.StepInto()
+                self._thread.Continue()
 
     def go(self) -> ReturnCode:
         self._process.Continue()
@@ -441,7 +441,7 @@ def _post_step_hook(self):
                 # Step again now to get to the breakpoint.
                 step_req_id = self.send_message(
                     self.make_request(
-                        "stepIn", {"threadId": self._debugger_state.thread}
+                        "continue", {"threadId": self._debugger_state.thread}
                     )
                 )
                 response = self._await_response(step_req_id)

>From 0a2cd3b2146310c9c3bfd9d8884c1e7e2eab2015 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <stephen.tozer at sony.com>
Date: Tue, 2 Sep 2025 18:27:46 +0100
Subject: [PATCH 2/2] Wrong target for Continue

---
 .../debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py            | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py b/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
index e3d0c4ec192d3..fa10b4914d45c 100644
--- a/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
+++ b/cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py
@@ -232,7 +232,7 @@ def step_in(self):
                     ):
                         stepped_to_breakpoint = True
             if stepped_to_breakpoint:
-                self._thread.Continue()
+                self._process.Continue()
 
     def go(self) -> ReturnCode:
         self._process.Continue()